Answer is B
how?

Have a look at below picture and see if something clicks??

It will certainly click, if still not understood,

3 P 8 => (8+3) => 11th letter from back

9 G 11 => (9+11) => 20th letter from back

2 U 4 =>(2+4) => 6th letter from back

3 W 1 => (3+1) => 4th letter from back

7 ? 18 => (7+18) => 25th letter from back

123 = 2×23 – 1 = 46 – 1 = 45
233 = 2×33 – 2 = 66 – 2 = 64
321 = 2X21- 3 = 42 – 3 = 39
840 = 2X40 – 8 = 80 -8 = 72
So
111 = 2X11 – 1 = 22 -1 = 21

Answer is 31.
How?
Look at columns, difference between second column number to first column number is same as difference between third column number and second column number, i.e.

c[i+1] – c[i] = c[i+2] – c[i]

lets assume missing number is X, thus
20 – 9 = X – 20
X = 40 -9 = 31

Here first number is the total number of alphabets
Second number is total number of vowels
And third number is 1, or may be you can say number of y.

Thus answer should be 931.

Scooter can run a maximum of 7.5kms.

How?

each tyre can run a maximum of 5kms, due to symmetry we can say that each type will run a 2.5kms with another tyre.

thus from tyres T1, T2 and T3

T1 and T2 will be used together for 2.5kms.

T1 and T3 will run another 2.5kms together.

and T2 and T3 will run another 2.5kms together.

thus scooter can go a total of 7.5kms.

it follows this logic square of 1st number- square root of 2nd number